The present invention relates to comminuting apparatus in general, especially to improvements in apparatus for comminuting industrial and/or domestic waste. More particularly, the invention relates to improvements in comminuting apparatus of the type wherein the material to be comminuted is fed into the open upper end of a housing to be advanced downwardly into a comminuting unit having at least one rotary knife and a stationary counterknife.
German Offenlegungsschrift No. 2,424,725 discloses an apparatus which is designed to comminute industrial and/or domestic waste materials including fragments and/or parts made of sheet metal or the like. When the housing of the apparatus simultaneously receives several metallic parts (e.g., cans), such parts are engaged by tongs constituting a rotary feeding device as well by a helical internal advancing surface of the housing to be delivered into the range of the comminuting unit. The feeding device crushes the metallic parts before they reach the comminuting unit. The latter is invariably clogged when the feeding device simultaneously delivers several crushed metallic parts. The just described apparatus exhibits similar drawbacks when the material to be comminuted constitutes or includes bulky books, bulky files, crates made of wood or like bulky constituents of industrial and/or domestic waste. It has been found that simultaneous feeding of several bulky constituents into the range of the comminuting unit often results in complete breakdown of the entire comminuting apparatus. Furthermore, the apparatus cannot properly process relatively soft constituents of waste, such as paper sheets, cardboard, fragments of textile materials, foodstuffs and the like; such materials are likely to pass through the comminuting unit without undergoing any or by undergoing a negligible comminuting action.
Another drawback of presently known comminuting apparatus, including the apparatus which is disclosed in the aforementioned German publication, is that the comminuted material is not positively expelled from the comminuting unit. For example, fragments of wet cardboard, accumulations of remnants of food or mixtures of remnants of food and adhesive substances are likely to pile up upstream of the outlet to cause clogging of the outlet proper and/or of the comminuting unit. This entails a stoppage of the comminuting unit or the entire apparatus.